1. Field of the Invention
The present invention is related to a method and a control device for detecting a dangerous driving condition of a vehicle.
2. Description of Related Art
Studies in accident research show that a vehicle's departure from the roadway is one of the most frequent causes of accidents in traffic situations and thus is responsible for a significant number of injuries or even fatalities among road users.
Today, there is a whole series of systems whose objective is to detect or prevent a vehicle's departure from the roadway. In this context, above all mention should be made of the optical systems that use passive methods (camera-based) or active methods (LASER measurement of the surroundings) in an attempt to identify the roadway and the roadway boundaries and to prevent a departure from the roadway, in interaction with the occupant or with the aid of an active steering system and control systems.
In contrast, other methods attempt already to fight the cause of the departure from the roadway. In this case, in particular systems that are applied in the field of driver monitoring should be mentioned. One frequent cause of departing from the roadway is that the driver falls asleep at the wheel, whether due to exhaustion or other influences such as illness or alcohol consumption.
Another class of protective measures involves preventing a departure from the roadway through active safety systems, such as ESP, for example. Such safety systems intervene, for example, when the vehicle starts skidding.
Another class involves structural measures on the edge of the road. In this case, above all mention should be made of guardrails that are erected on the edge of the road or between two traffic lanes having opposite directions of travel.
In the field of suspension technology, so-called active suspensions are increasingly common. In these systems, a controlled system adjusts the suspension to the driving behavior and road condition. The controlled system is typically made up of sensors that measure the compression rate for each wheel suspension. With the aid of this information, a control device determines parameters that in turn adjust the damping properties of the dampers via valves. A corresponding driving dynamics control system of a motor vehicle is described in published German patent application document DE 100 50 420 A1, for example.
In the field of algorithms for accident detection and crash characterization, there are methods from the field of statistical learning methods and cognitive systems or classification methods, e.g., k-nearest neighborhood classification, support vector machines, hidden Markov methods, and vector quantization.
Methods for automatically correcting a condition variable of a vehicle departing from a predefined roadway are also known. In this case, if the vehicle has departed from the predefined roadway, a vehicle control system in the vehicle may be re-parametered in such a way that an intervention specified by the driver is converted in a reduced manner into a modification of a vehicle condition variable. This is to prevent an excessively strong counter-steering of the driver, so as to prevent the build-up of an oscillation in the vehicle.
It is known from published German patent application document DE 10 2005 003 177 A1 that if the correct lane is departed from, a counter-steering torque can be generated in the steering system of the vehicle, which counteracts the steering angle applied by the driver. This can help prevent vehicle accidents. Such lane keeping systems (lane keeping assist) aim to prevent an accident by keeping the vehicle in the predefined lane or by bringing it back into the lane. A complex sensor system is required for this purpose. The sensor system makes it possible to permanently monitor the current vehicle position in relation to the roadway, and in the event of an unacceptable deviation from the setpoint trajectory, a corresponding counter-steering torque can be generated.
In accordance with a vehicle control system known from published German patent application document DE 195 06 364 C2, the current vehicle position is determined with the aid of a navigation device. The vehicle speed can be corrected by an automatic braking and the vehicle position can be corrected by an automatic adjustment of the steering torque and of the steering angle, so that the vehicle can safely drive through a curve, for example.
In the “early pole crash detection” function, when skidding is detected by the ESP control device, the plausibility and/or a threshold adjustment for the triggering of lateral restraining devices is simplified. In this way, a faster triggering of the same is made possible.
The previously known methods have some deficiencies. Camera-based and laser-based methods offer the option of detecting the danger condition “departing from the roadway” in advance; however, both suffer from the fact that they are currently not yet sufficiently reliable. Thus, camera-based methods still have some problems in the case of insufficient lighting and poor and unclear roadway markings. The same holds true for the laser-based systems. For this reason, these methods are not yet produced and implemented on a large-scale. Additionally, such systems are associated with very high costs.
In the field of sleep detection, different systems are considered. However, there is still no market penetration in this instance either. The primary disadvantage of such systems is that only one of the causes of the departure from the roadway is detected.
The ESP system can prevent the departure from the roadway due to uncontrolled driving conditions in that it prevents the cause in this case, namely, the loss of control of the vehicle. However, if the vehicle departs from the road without skidding, for example, due to the inactivity of the driver, the system will not respond and thus will not provide any protection.
Structural measures always have the disadvantage of high expense (planning, approval) and of high costs (procurement, maintenance, repair). Apart from this, structural measures can even result in increased risk to other road users, such as motorcycle drivers, for example.